Intracarotid drug infusions for the treatment of brain tumors appear to offer a significant advantage in terms of optimal distribution when the drug has either a high affinity for the tumor only, a high rate of blood-tumor exchange, or a rapid rate of metabolism or when carotid blood flow is low. Chronic alterations in body tissue and fluid levels of vitamin A in rhesus monkeys were found to produce no detectable changes in CSF pressure and absorption changes which occur when blood is injected into the subarachnoid space (subarachnoid hemorrhage) are substanially alleviated when the injected blood is heparinized. We have evidence in the rhesus monkey that albumin is moved from brain to blood by a special transport system or "pump". A critical examination of the Oldendorf BUI technique indicated that this procedure for measuring bloodbrain barrier permeability has blood flow, sampling time, and reference material limitations. We have also found that the regulation of brain solute levels is only slightly controlled by the sink action of th CSF. Finally we demonstrated that brain edema occurs in two species of fish. BIBLIOGRAPHIC REFERENCES: Ausman, J. I., Levin, V. A., Brown, W. E., Rall, D. P. and Fenstermacher, J. D.: Brain tumor chemotherapy: pharmacologic principles derived from a monkey brain tumor model. Jour. Neurosurg. 46: 155-164, 1977. Fenstermacher, J. D. and Patlak, C. S.: The movement of water and solutes in the brains of mammals. In Pappius, H. and Feindel, W. (Eds.): Dynamics of Brain Edema. Berlin, Springer-Verlag, 1977, pp. 87-94.